Sort security vulnerabilities by priority in MR widget
With !3207 (merged), we will show security vulnerabilities.
These should be sorted in order of priority: High, Medium, Low, and no priority shown.
Sort the file directly at the origin, once for all. This solution doesn't require any frontend change, because the order shown is the same as the one in the data file.
Actual order is: High, Medium, Low, Unknown, everything else.